Photoluminescence of Zinc Oxide Nanowires: The Effect of Surface Band Bending

Figure 4

Schematics of the energy band diagram (not to scale) for (a) as-grown, (b) oxygen annealed, and (c) after vacuum annealed samples, illustrating the band bending and charged states of 𝑉_o near the surface. Solid dots are electrons and empty circles are holes. The vertical dotted lines depict the radiative recombination processes, where GL is plotted in green and the UV luminescence in blue. The Fermi level is the red dashed line. The dissociation of the electron-hole pairs is indicated with arrows.

(a)

(b)

(c)